Modular implant part and knee joint prosthesis

The present disclosure relates to the subject matter disclosed in German patent application No. 10 2007 028 087.6 of Jun. 11, 2007 which is incorporated herein by reference in its entirety and for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component.

Furthermore, the present invention relates to a knee joint prosthesis comprising a first implant part in the form of a femoral part, a second implant part in the form of a tibial part and a third implant part in the form of a meniscus part, wherein the first and/or the second implant part is a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component.

Modular implant parts of the type described hereinabove are used in order to obtain particularly stable embedding of the implant in the bone. For this purpose, shafts in the form of extension shafts are used and they are inserted into a medullary cavity of a partially resected bone, for example, the femur or the tibia of a patient so as to enable the shafts and hence the implant part to be better supported on the bone. The shafts for the respective implant part are usually available in different lengths and angles. Moreover, in order to enable the position of the shaft relative to the implant component to be ideally matched to the anatomy of a patient, it is advantageous if the shafts are adapted to be mounted on the implant component in different positions.

Examples of modular implant parts of this type are known from U.S. Pat. No. 5,782,920, US 2003/0055508 A1 and U.S. Pat. No. 5,290,313. The disadvantage of the implant parts described in the aforesaid documents is, however, that the shaft can only be mounted on the implant component at defined angular positions or with a defined lateral displacement using appropriate adapters so that, in turn, a multiplicity of appropriate adapters is necessary for different positions of the shaft.

Consequently, it would be desirable to provide a modular implant part and a knee joint prosthesis of the type described hereinabove which would allow fixing the shaft the implant component at a multiplicity of desired positions in a simple manner.

SUMMARY OF THE INVENTION

In accordance with the invention, it is suggested in the case of a modular implant part of the type described hereinabove that, in a mounting disposition, the connecting device is formed in such a manner that the shaft is adapted to be moved into different translatory positions by a translatory movement in a direction transverse or substantially transverse to its longitudinal axis and that, in an implantation disposition, the shaft is adapted to be fixed immovably to the implant component in one of the different translatory positions.

An improved modular implant part of this type enables one to manage without a multiplicity of adapters or shafts in order to connect the implant component to a shaft and implant it in the most varied of implantation dispositions. Due to the translatory movements in a direction transverse or substantially transverse to the longitudinal axis of the shaft that are made possible by means of the connecting device, a lateral displacement of the shaft on the implant component can be established in the desired manner. Different adapters or different shafts for the purposes of mounting on the implant component in differing positions are therefore superfluous. This reduces the manufacturing complexity and thus the costs of the modular implant part on the one hand, whilst increasing the facility of observing the process in an operating theatre on the other, because the operating surgeon can match the modular implant part directly to the anatomy of the respective patient. Thus, in particular, optimal coverage of a partially resected bone by the implant component can be ensured in a simple and safe manner.

Advantageously, the connecting device is formed in such a manner that it is possible for different translatory positions to be set in step-less manner in the mounting disposition. Thus, the modular implant part can be adapted to the anatomy of a patient in an optimal and step-less manner.

It is expedient, if, in the mounting disposition, the shaft is rotatable about an axis of rotation, which runs parallel or substantially parallel to the longitudinal axis of the shaft, into different rotary positions relative to the implant component. This arrangement enables the shaft to be positioned on the implant component practically at will because it can be moved into different translatory positions and rotated into different rotary positions, whereby any arbitrary superimposition of the translatory and rotary movements of the shaft relative to the implant component is possible.

In order to enable the shaft to be fixed to the implant component in the implantation disposition in a durable and secure manner, it is expedient if, in the implantation disposition, the shaft is adapted to be fixed immovably to the implant component by the connecting device in one of the different rotary positions. In particular, the connecting device can also be formed in such a manner that it is possible to fix the translatory position and the rotary position independently of each other. In particular, this permits a desired translatory position to be firstly set and fixed and then subsequently, for the shaft to be moved into a desired rotary position. It is self-evident that the reverse procedure is also conceivable.

In principle, it would be conceivable to form the implant part in such a manner that the shaft is adapted to be fixed to the implant component in only certain defined rotary positions. Advantageously however, the connecting device is formed in such a manner that it is possible to set-up differing rotary positions in step-less manner in the mounting disposition. In this manner, an operating surgeon is not subjected to any restriction in regard to the adjustment of the modular implant part. He can therefore match it individually and optimally to the anatomy of the patient.

In order to enable the shaft to be connected to the implant component in a simple manner, it is expedient if the connecting device comprises at least one adapter which, in the mounting disposition, is adapted to be fixed to the implant component on the one hand and to the shaft on the other. This permits the modular implant part to be formed with a minimum number of parts.

The structure of the modular implant part can be further simplified if the at least one adapter comprises an adapter element which is symmetrically or substantially symmetrically formed. This additionally simplifies the production process and reduces the costs of the implant part.

In order to enable the implant component to be connected to the adapter in a simple manner, it is advantageous for the implant component to comprise a first coupling member which is in engagement with the adapter in force-locking and/or shape-locking manner in the implantation disposition. In particular, the stability of the implant part can thereby be established in the desired manner.

Preferably, the first coupling member is constructed in the form of a coupling projection. For example, the shaft can be fixed directly to the coupling projection with or without an adapter. In addition, the coupling projection can, for example, engage in a simple manner with a corresponding coupling seating in the implantation disposition, this thereby permitting particularly good support of the shaft on the implant component.

It is advantageous if the connecting device comprises a first coupling device for immovably fixing the at least one adapter to the implant component in the implantation disposition. With the aid of such a coupling device, the adapter, and via it the shaft too, can be fixed to the implant component in a simple and secure manner.

A particularly simple construction of the first coupling device can be achieved in that the first coupling device comprises at least two first coupling elements which are in engagement in the implantation disposition, and in that the implant component comprises one of the at least two first coupling elements and in that the adapter comprises another of the at least two first coupling elements.

The modular implant part can be constructed in a particularly compact manner if the first coupling member comprises one of the at least two first coupling elements.

The adapter and the implant component can be interconnected in a secure and durable manner if one of the at least two first coupling elements comprises an internally threaded section and another of the at least two first coupling elements comprises a corresponding externally threaded section. The two parts that are to be interconnected can thus be screwed together in a simple manner.

Advantageously, one of the at least two first coupling elements comprises a recess and another of the at least two first coupling elements comprises a projection which enters the recess in the implantation disposition. Thus, in particular, a temporary connection can be established between the parts that are to connected together in the mounting disposition, but nevertheless a relative movement therebetween is still possible.

The construction of the coupling device is particularly simple if the recess is in the form of a groove and the projection is in the form of a screw, whereby at least one part of the screw enters the groove in the implantation disposition. Thus, in particular, the implant part can be transferred from the mounting disposition into the release position and/or vice versa by a simple movement of the screw.

In order to keep the number of necessary parts of the modular implant part as small as possible, it is expedient if the adapter and the first coupling element comprised thereby are formed in one piece. Furthermore, the stability of the implant part can also be increased thereby.

In order to enable a particularly secure connection between the adapter or the shaft and the implant component to be established, it is expedient if the first coupling device comprises a first fastening element, if the first fastening element comprises the at least one first coupling element of the adapter and if, in the implantation disposition, the first fastening element is supported on the adapter on the one hand and is connected to the implant component on the other hand, or vice versa. In particular, such an arrangement enables the adapter to be applied to the implant component from one side without the need to provide a through opening in the implant component. For example, the first fastening element can be in the form of a screw having a threaded section which passes through a through opening in the adapter, a head which is supported on the adapter, and the threaded section thereof being adapted to be screwed to the implant component.

Furthermore, in accordance with a preferred embodiment of the invention, provision may be made for the connecting device to comprise a second coupling device for immovably fixing the at least one adapter to the shaft in the implantation disposition. Accordingly, the adapter can be fixed to the shaft with the aid of the second coupling device. Preferably, in different positions.

It is advantageous if the second coupling device comprises at least two second coupling elements which are in engagement in the implantation disposition, and if the shaft comprises one of the at least two second coupling elements, and if the adapter comprises another one of the at least two second coupling elements. In particular, the two second coupling elements can be formed in such a manner that the shaft and the adapter are adapted to be fixed relative to one another in mutually different translatory positions in the implantation disposition.

The construction of the implant part is particularly simple if the shaft comprises a second coupling member which is in engagement with the adapter in force-locking and/or shape-locking manner in the implantation disposition. In particular, the shaft and the adapter can engage with one another in different translatory positions and/or rotary positions in the implantation disposition.

In order to construct the implant part in a yet more compact manner, it is advantageous if the second coupling member comprises one of the at least two second coupling elements.

The manufacture of the implant part is particularly simple if the second coupling member is constructed in the form of a coupling projection. It is self-evident that it could also be constructed in the form of a coupling seating.

In order to enable the adapter and the shaft to be interconnected in a simple manner and in particular, to enable them to be screwed together, it is advantageous if one of the at least two second coupling elements comprises an internally threaded section and if another one of the at least two second coupling elements comprises a corresponding externally threaded section. In addition, threaded sections are simple and economical to manufacture.

Moreover, it can be expedient if one of the at least two second coupling elements comprises a recess and if another one of the at least two second coupling elements comprises a projection which enters the recess in the implantation disposition. Thus in particular thereby, a positive connection between the two second coupling elements can be established in a simple manner.

Preferably, the recess is in the form of a groove and the projection is in the form of a screw, whereby at least one part of the screw enters the groove in the implantation disposition. In particular, this arrangement further simplifies the construction of the modular implant part.

The number of parts necessary for the construction of the modular implant part can be further reduced if the adapter and the second coupling element comprised thereby are formed in one piece.

In order to achieve simple attachment of the adapter to the shaft, it is expedient if the second coupling device comprises a second fastening element which connects the adapter to the shaft in the implantation disposition.

A particularly compact construction of the modular implant part can be achieved if the second fastening element comprises the at least one second coupling element of the adapter and if, in the implantation disposition, the second fastening element is supported on the adapter on the one hand and is connected to the shaft on the other. In particular, such an arrangement enables a screw to be envisaged as the second fastening element, the head thereof being supported on the adapter and the threaded section thereof being adapted to be screwed to the shaft.

It is advantageous if the connecting device comprises a first guidance device for guiding a movement of the adapter and the implant component relative to each other in the mounting disposition. The guidance device enables the shaft to be transferred relative to the implant component in a defined manner from one translatory position into another translatory position and/or from one rotary position into another rotary position.

It is particularly advantageous if the first guidance device comprises a rotary guide means. The shaft and the implant component can thereby be rotated relative to each other in a defined manner.

The construction of the implant part is particularly compact if the first guidance device comprises the first coupling member. The number of necessary parts in the implant part can thereby be minimized.

Furthermore, in accordance with a preferred embodiment of the invention, provision may be made for the connecting device to comprise a second guidance device for guiding a movement of the adapter and the shaft relative to each other in the mounting disposition. Thus, in particular thereby, the shaft can be moved relative to the adapter and hence the shaft relative to the implant component in a defined manner.

The construction of the implant part is particularly simple if the second guidance device comprises a linear guide means. With the aid of such a linear guide means, it is possible to set a defined displacement of the shaft and the implant component relative to each other in a simple manner.

It is advantageous, if the second guidance device comprises at least one guide groove formed on the adapter and/or on the shaft and if the second coupling member is guided in the guide groove in movable manner in the mounting disposition. Formation of a guide groove is technically simple from both a constructional and manufacturing point of view and enables defined and stable guidance of the shaft and the adapter relative to each other to be obtained. In particular, the guide groove can be in the form of a straight-line or curved.

Expediently, the second guidance device comprises the second coupling member. In this manner, the number of components needed for the production of the modular implant part can be further reduced.

As already stated above, it is expedient, if the shaft and the implant component can be adjusted relative to each other in step-less manner. However, it can also be expedient if provision is made for a positioning device for positioning the shaft and the implant component relative to each other in a plurality of discrete positions. In particular, the stability of the modular implant part can be thereby increased. Furthermore, it is also simpler for some operating surgeons if a translatory position or a rotary position can be selected from a plurality of discrete positions in order to match the modular implant part to the anatomy of the patient.

Advantageously, the positioning device comprises a rotary positioning device for positioning the shaft and the implant component relative to each other in a plurality of discrete rotary positions. Thus, certain specific relative angular positions of the shaft and the implant component can be predefined by the manufacturer by appropriate construction of the rotary positioning device. In particular, relative positions which would not be desired at all in practice can also be completely excluded thereby.

Preferably, the positioning device comprises a linear positioning device for positioning the shaft and the implant component relative to each other in a plurality of discrete translatory positions. Here too, desirable frequently occurring translatory positions can be predefined for an operating surgeon in order to position the shaft and the implant component relative to each other in a defined manner. Self-evidently, the positioning device can be formed in such a manner that the linear positioning device and the rotary positioning device are effective and can be used mutually independently. This means, in particular, that a translatory position can be altered prior to, during or after a change of a rotary position.

The construction of the positioning device is particularly simple if it comprises at least two sets of teeth which are in engagement in the implantation disposition and if sets of teeth are provided on the implant component and on the adapter and/or on the adapter and on the shaft. Sets of teeth are simple to manufacture and are best suited to establishing defined translatory or rotary positions.

Advantageously, the sets of teeth are in the form of toothed rings and/or in the form of linear sets of teeth. Toothed rings are excellently suited to the formation of rotary positioning devices, linear sets of teeth are excellent for the formation of linear positioning devices. The sets of teeth can be formed such that they are oriented in each case in the direction of the parts of the implant part that fit together or else transverse thereto. In particular, rows of tooth can be provided with teeth which extend in parallel with a longitudinal axis of the shaft or which extend perpendicularly thereto.

Expediently, there is provided at least one securing device for securing the first and/or second coupling device in the implantation disposition. The connection of the shaft to the implant component is additionally improved by the securing device, whereby a direct or indirect connection to the securing device is possible.

The construction of the securing device is particularly simple if it comprises a lock nut. Thus, in particular, parts that are screwed to one another can be secured in a connecting position, in the implantation disposition for example.

In order to prevent the medullary cavity of a bone being damaged or in order to minimize the risk thereof by the insertion of the shaft, it is advantageous if a plurality of shafts of different lengths are provided. In particular thereby, an implant-set can also be formed which comprises a modular implant part and a multiplicity of shafts of different lengths and/or different shapes, for example, of different curvature and different diameters.

In accordance with a preferred embodiment of the invention, provision can be made for the implant component to comprise artificial femoral condyles between which a depression is formed. In particular, a femoral part of a knee joint prosthesis can be formed with the aid of an implant component of this type. Preferably, the implant part forms a femoral part of a knee joint prosthesis. In particular thereby, a part of the femur which forms the natural condyles can be optimally replaced.

Furthermore, it can be expedient if the implant part forms a tibial part of a knee joint prosthesis. Such an implant part can be optimally matched to the anatomy of the part of the tibia on the knee joint side.

In order to enable a meniscus part to be supported on a knee joint prosthesis in a simple and secure manner, it is expedient if the implant component comprises a plate-like tibia plateau. In particular, a meniscus part can be placed flat upon the tibia plateau and moved relative thereto.

Furthermore, in accordance with the invention, it is suggested in the case of a knee joint prosthesis of the type described hereinabove that the connecting device is formed in such a manner that, in a mounting disposition, the shaft is adapted to be moved into different translatory positions by a translatory movement in a direction transverse or substantially transverse to its longitudinal axis and that, in an implantation disposition, the shaft is adapted to be fixed immovably to the implant component in one of the different translatory positions.

Such a knee joint prosthesis can be matched in an optimal manner to the anatomy of a patient. In particular, it can be designed in such a manner that the implant component ensures maximum coverage of a partially resected bone end.

Furthermore, it is expedient if the first and/or the second implant part is one of the modular implant parts described above. Such an implant part then has the advantages mentioned above in connection with the embodiments described.

The following description of preferred embodiments of the invention serves for a more detailed explanation taken in conjunction with the drawing. Therein:

BRIEF DESCRIPTION OF THE DRAWINGS

<figref idrefs="DRAWINGS">FIG. 1</figref>: shows an exploded view of a first exemplary embodiment of a modular implant part;

<figref idrefs="DRAWINGS">FIG. 2</figref>: a side view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 1</figref> in an implantation disposition;

<figref idrefs="DRAWINGS">FIG. 3</figref>: a sectional view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 2</figref> along the line <b>3</b>-<b>3</b> in <figref idrefs="DRAWINGS">FIG. 1</figref> in the implantation disposition;

<figref idrefs="DRAWINGS">FIG. 4</figref>: a perspective view of a second exemplary embodiment of a modular implant part;

<figref idrefs="DRAWINGS">FIG. 5</figref>: an exploded view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 4</figref>;

<figref idrefs="DRAWINGS">FIG. 6</figref>: a perspective view of a third exemplary embodiment of a modular implant part;

<figref idrefs="DRAWINGS">FIG. 7</figref>: an exploded view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 6</figref>;

<figref idrefs="DRAWINGS">FIG. 8</figref>: an enlarged illustration of a detail of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 7</figref>;

<figref idrefs="DRAWINGS">FIG. 9</figref>: a perspective view of a fourth exemplary embodiment of a modular implant part;

<figref idrefs="DRAWINGS">FIG. 10</figref>: an exploded view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 9</figref> from below;

<figref idrefs="DRAWINGS">FIG. 11</figref>: an exploded view of the implant part depicted in <figref idrefs="DRAWINGS">FIG. 9</figref> from above; and

<figref idrefs="DRAWINGS">FIG. 12</figref>: a side view of a fifth exemplary embodiment of a modular implant part.

DETAILED DESCRIPTION OF THE INVENTION

A first exemplary embodiment of a modular implant part is provided with the general reference symbol <b>10</b> in <figref idrefs="DRAWINGS">FIGS. 1 to 3</figref>. It is illustrated in the form of a tibial part <b>12</b> of a knee joint prosthesis which, furthermore, comprises a femoral part and optionally too, a likewise not illustrated meniscus part.

The implant part <b>10</b> comprises an implant component <b>14</b>, an elongated, round rod-shaped shaft <b>16</b> as well as a connecting device <b>18</b> for connecting the implant component <b>14</b> to the shaft <b>16</b>.

The implant component <b>14</b> comprises a plate which is substantially kidney-shaped in a top view and forms a tibia plateau <b>20</b> the upper surface <b>22</b> and lower surface <b>24</b> of which are completely flat in the exemplary embodiment illustrated in the Figures. A coupling member <b>26</b> in the form of a stud-like projection <b>28</b> extends centrally away from the middle of the lower surface <b>24</b>, this member being provided with an external thread <b>30</b> over its entire length. The coupling member <b>26</b> is connected in one piece manner to the implant component <b>14</b> and thus in toto forms a threaded bolt which defines a longitudinal axis <b>32</b>.

The connecting device <b>18</b> comprises an adapter <b>34</b> which, in turn, comprises an adapter element <b>36</b> that is mirror-symmetrical relative to a mirror plane containing the longitudinal axis <b>32</b>, a coupling element <b>38</b> in the form of a slide block <b>40</b> and a lock nut <b>42</b>. The lock nut <b>42</b> has an internal thread <b>44</b> which is formed so as to correspond to the external thread <b>30</b>. In the cross section transverse to the longitudinal axis <b>32</b>, the lock nut <b>42</b> has a hexagonal outer contour.

An upper portion of the adapter element <b>36</b> comprises a further coupling element <b>46</b> in the form of an internally threaded section <b>48</b> of a blind hole <b>50</b> which is formed such as to be coaxial with the longitudinal axis <b>32</b>. An upper end <b>52</b> of the adapter element <b>36</b> is thus in the form of a hexagon nut whose height corresponds to about a quarter of the overall length of the adapter element <b>36</b> parallel to the longitudinal axis <b>32</b>. The coupling elements <b>38</b> and <b>46</b> form first coupling elements of a first coupling device <b>54</b> for the purposes of fixing the adapter <b>34</b> to the implant component <b>14</b>.

The lower half of the adapter element <b>36</b> has a T-shaped guide groove <b>56</b> which is oriented transversely relative to the longitudinal axis <b>32</b> and is formed by two cuboidal through openings which are oriented perpendicularly to each other. The adapter element <b>36</b> is downwardly open by virtue of a slot <b>58</b> which forms a part of the guide groove <b>56</b> and is, in effect, the perpendicular stroke of the “T”. In addition, the guide groove <b>56</b> is formed in such a manner that the cuboidal slide block <b>40</b>, which is provided with an internally threaded boring <b>60</b>, can be shifted transversely relative to the longitudinal axis <b>32</b> in a section of the guide groove <b>56</b> which quasi forms the cross-stroke of the “T”.

The distal end <b>62</b> of the shaft is rounded off in hemispherical manner. The proximal end of the shaft comprises a second coupling member <b>64</b> in the form of a threaded bolt <b>66</b> which is coaxial with respect to a longitudinal axis <b>68</b> of the shaft <b>16</b> whilst the outer diameter thereof is somewhat reduced with respect to the shaft <b>16</b>. This thus results in a ring-like surface <b>70</b> that faces in the proximal direction and is oriented transversely of the longitudinal axis <b>68</b>. The threaded bolt <b>66</b> comprises a second coupling element <b>72</b> in the form of an external thread which is formed such as to correspond to an internal thread of the internally threaded boring <b>60</b>. The slot <b>58</b> is of such a width that the threaded bolt <b>66</b> can be introduced therethrough coming from the distal end, i.e. in a direction towards the implant component <b>14</b>, and it can also be displaced in the slot <b>58</b> transversely relative to the longitudinal axis <b>68</b>. The connecting device <b>18</b> thus comprises not only the first coupling device <b>54</b>, but also a second coupling device <b>74</b> which comprises the second coupling member <b>64</b> as well as the second coupling element <b>72</b> and the internally threaded boring <b>60</b> of the slide block <b>40</b> likewise forming a second coupling element <b>76</b>.

As will be explained in more detail hereinafter, the implant part <b>10</b> comprises a first guidance device <b>78</b> in the form of a rotary guide means <b>80</b> for guiding rotational movement of the adapter <b>34</b> and the implant component <b>14</b> relative to each other. It comprises, in particular, the first coupling member <b>26</b>. Furthermore, there is provided a second guidance device <b>82</b> for guiding movement of the adapter <b>34</b> and the shaft <b>16</b> relative to each other, this being in the form of a linear guide means <b>84</b>. Moreover, there is provided a securing device <b>86</b> which comprises the lock nut <b>42</b> for securing a connection of the first coupling device <b>54</b> in an implantation disposition in which all the parts of the implant part <b>10</b> are firmly connected to one another.

The, in all, five parts of the implant part <b>10</b> are assembled as follows. Firstly, the lock nut <b>42</b> is screwed onto the first coupling member <b>26</b>. Then, the adapter element <b>36</b> is likewise screwed onto the coupling member <b>26</b>. The rotary guide means <b>80</b> comprising the first coupling member <b>26</b> and the internally threaded section <b>58</b> of the blind hole <b>50</b> enables arbitrary alignment of the adapter element <b>36</b> about the longitudinal axis <b>32</b>, i.e. the guide groove <b>56</b> can be adjusted into any rotary position with respect to the longitudinal axis <b>32</b>. As long as the lock nut <b>42</b> is not tightened up against the end <b>52</b> of the adapter element <b>36</b>, the implant part <b>10</b> adopts a so-called mounting disposition in which another relative movement of the adapter element <b>36</b> and the implant component <b>14</b> is still possible.

Moreover, the second coupling member <b>64</b> is screwed into the slide block <b>40</b>, namely, in such a manner that the spacing between a lower surface <b>88</b> and the ring-shaped surface <b>70</b> is greater than the height of the slot <b>58</b> parallel to the longitudinal axis <b>68</b>. The slide block <b>40</b> together with the shaft <b>16</b> screwed therein can then be slid transversely relative to the longitudinal axis <b>68</b> into the guide groove <b>56</b>, whereby the threaded bolt <b>66</b> passes through the slot <b>58</b>. The linear guide means <b>84</b> comprising the slide block <b>40</b> and the guide groove <b>56</b> enables step-less adjustment of the shaft <b>16</b> and the adapter element <b>36</b> relative to each other in the mounting disposition, in which they are not as yet firmly connected together. Should the slide block <b>40</b> and the coupling member <b>64</b> be screwed firmly together, the ring-shaped surface <b>70</b> presses against a distal end face <b>90</b> of the adapter element <b>36</b> running transversely relative to the longitudinal axis <b>68</b> so that the shaft <b>16</b> is held clamped onto the adapter <b>34</b> in the implantation disposition.

When the implant part <b>10</b> is adjusted in the desired manner, i.e. a relative position of the shaft <b>16</b> and the adapter <b>34</b> as well as a desired rotary position of the adapter <b>34</b> relative to the implant component <b>14</b>, the first and second coupling device <b>54</b> and <b>74</b> can be transferred from the mounting disposition into the implantation disposition, namely as already described above for the second coupling device, by screwing the shaft <b>16</b> into the slide block <b>40</b> and also by mutually tightening the lock nut <b>42</b> against the end <b>52</b> of the adapter element <b>36</b>. Due to the second guidance device <b>82</b> comprised by the connecting device <b>18</b>, the shaft <b>16</b> can, in the mounting disposition, be moved in step-less manner into different translatory positions by means of a translatory movement in a direction transverse to the longitudinal axis <b>68</b>, such positions defining a lateral displacement <b>92</b>, i.e. a spacing between the longitudinal axes <b>32</b> and <b>68</b>. Thus, in toto, the shaft <b>16</b> can be fixed immovably to the implant component <b>14</b> in any rotary position about the longitudinal axis <b>32</b> and with any arbitrary displacement <b>92</b> relative thereto.

A second exemplary embodiment of an implant part provided with the general reference symbol <b>110</b> is illustrated in <figref idrefs="DRAWINGS">FIGS. 4 and 5</figref>. It differs from the implant part <b>10</b> by virtue of the construction of the connecting device <b>118</b>. Consequently, for the sake of clarity hereinafter, the parts of the implant part <b>110</b> which correspond to parts of the implant part <b>10</b> are provided with reference symbols which exhibit the same two end digits as the reference symbols used for identifying the parts of the implant part <b>10</b>.

The implant part <b>110</b> likewise forms a tibial part <b>112</b> having a plate-like implant component <b>114</b>. From a lower surface <b>124</b> thereof, there protrudes a first coupling member <b>126</b> in the form of a cylindrical projection <b>128</b> which defines a longitudinal axis <b>132</b>. Moreover, a peripheral annular groove <b>130</b> having a wedge-shaped profile is formed in the projection <b>128</b>.

Furthermore, the implant part <b>110</b> comprises a shaft <b>116</b> as well as a connecting device <b>118</b> for connecting the implant component <b>114</b> to the shaft <b>116</b>.

An adapter <b>134</b> of the connecting device <b>118</b> comprises an adapter element <b>136</b> which is very similar in terms of its fundamental construction to the adapter element <b>36</b>. It takes the form of a cylindrical section and is formed symmetrically relative to a plane of symmetry containing the longitudinal axis <b>132</b>. The upper or proximal-side end <b>152</b> of the adapter element <b>136</b> has a blind hole <b>150</b> which is open in the proximal direction and is formed coaxially relative to the longitudinal axis <b>132</b>, it also forming a coupling element <b>146</b> of a first coupling device <b>154</b>. Furthermore, the latter also comprises the coupling member <b>126</b>. The coupling member <b>126</b> is adapted to be inserted into the blind hole <b>150</b> in positive manner so that the adapter element <b>136</b> is rotatable relative to the implant component <b>114</b>.

For the purposes of securing a connection between the adapter <b>134</b> and the implant component <b>114</b> in the implantation disposition in which all the parts of the implant part <b>110</b> are firmly connected together, there is provided a securing device <b>186</b>. It comprises three set-screws <b>142</b> which are formed such as to correspond to three threaded borings <b>143</b> the longitudinal axes <b>145</b> of which define a plane extending perpendicularly to the longitudinal axis <b>132</b>, are mutually displaced by a respective angle <b>147</b> of 120° and pass through a wall of the adapter element <b>136</b> surrounding the blind hole <b>150</b>. Each of the set-screws <b>142</b> has a conical point <b>149</b> which can engage in the annular groove <b>130</b> when the set-screw <b>142</b> is screwed into the respective threaded boring <b>143</b>. As long as the set-screws <b>142</b> only engage in the annular groove <b>130</b>, but not however such that their points <b>149</b> press against it, the adapter element <b>136</b> can be rotated relative to the implant component <b>114</b>. Thus, the implant part <b>110</b> also comprises a first guidance device <b>178</b> in the form of a rotary guide means <b>180</b> which comprises the coupling member <b>126</b> and the blind hole <b>150</b>.

The lower end of the adapter element <b>136</b> has a guide groove <b>156</b> which is T-shaped in longitudinal section and has an open slot <b>158</b> oriented in the distal direction. In the vicinity of the guide groove <b>156</b>, in which the slide block <b>40</b> was guided in the case of the guide groove <b>56</b>, there are formed two threaded borings <b>160</b> the longitudinal axes <b>161</b> of which are aligned coaxially of each other, whereby the longitudinal axes <b>161</b> intersect the longitudinal axis <b>132</b> perpendicularly. Furthermore, the longitudinal axes <b>161</b> are oriented perpendicularly relative to a plane defined by the slot <b>158</b>.

The shaft <b>116</b> has a distal end <b>162</b> which is rounded off in hemispherical manner. At the proximal end of the elongated, round rod-shaped shaft <b>116</b>, there is formed a second coupling member <b>164</b> which is in the form of a projection <b>166</b> that is T-shaped in longitudinal section and is formed in a manner corresponding to the guide groove <b>156</b>, so that the second coupling member <b>164</b> is adapted to be inserted into the guide groove <b>156</b> in a direction transverse to a longitudinal axis <b>168</b> of the shaft <b>116</b> and is displaceable therein. The shaft <b>116</b> can be fixed to the adapter element <b>136</b> in the implantation disposition with the aid of a further securing device <b>187</b> which comprises two clamping screws <b>188</b> that are formed in a manner corresponding to the threaded borings <b>160</b>. In the implantation disposition, the end faces <b>190</b> of the clamping screws <b>188</b> press against side faces <b>140</b> of the projection <b>166</b> which face away from the longitudinal axis <b>168</b> and are diametrically opposite.

A second coupling device <b>174</b> for connecting the shaft <b>116</b> and the adapter <b>134</b> comprises the second coupling member <b>164</b>, the guide groove <b>156</b> and also the clamping screws <b>188</b> held in the threaded borings <b>160</b>.

A second guidance device <b>182</b>, which is constructed in the form of a linear guide means <b>184</b>, comprises the projection <b>166</b> as well as the guide groove <b>156</b> which enables a translation of the shaft <b>116</b> relative to the adapter <b>134</b> in a direction transverse to the longitudinal axis <b>168</b>. Consequently, an operating surgeon can match the implant part <b>110</b> individually to the anatomy of a patient, namely, in that the shaft <b>116</b> can be shifted relative to the adapter <b>134</b> in a desired manner in order to establish a displacement <b>192</b> between the longitudinal axes <b>132</b> and <b>168</b>, and in that the adapter <b>134</b> can be rotated relative to the implant component <b>114</b> about the longitudinal axis <b>132</b> in the mounting disposition.

A further modular implant part in the form of a tibial part <b>212</b> that is provided with the general reference symbol <b>210</b> is illustrated in <figref idrefs="DRAWINGS">FIGS. 6 to 8</figref>. It comprises an implant component <b>214</b>, a shaft <b>216</b> and a connecting device <b>218</b> for connecting the shaft <b>216</b> to the implant component <b>214</b>.

The implant component <b>214</b> comprises a plate-like tibia plateau <b>220</b> which corresponds to the tibia plateau <b>20</b>. For the sake of simplicity hereinafter, reference symbols having identical end digits are again used for the designation of parts of the implant part <b>210</b> which are identical or functionally similar to the parts of the implant part <b>10</b>.

A first coupling member <b>226</b>, namely, in the form of a stud-like projection <b>228</b>, protrudes perpendicularly from a lower surface <b>224</b>.

The connecting device <b>218</b> comprises an adapter <b>234</b> which can be connected to the implant component <b>214</b> on the one hand and to the shaft <b>216</b> on the other. The adapter element <b>236</b> is formed from a cylindrical base body and has a cylindrical blind hole <b>250</b> on the proximal side. The base <b>251</b> of the blind hole <b>250</b> is provided with a boring <b>253</b> which is oriented coaxially relative to a longitudinal axis <b>232</b> of the projection <b>228</b> in like manner to the blind hole <b>250</b>.

Furthermore, a first coupling device <b>254</b> for connecting the adapter element <b>236</b> to the implant component <b>214</b> comprises a fastening element <b>294</b> in the form of a screw <b>296</b> having a head <b>298</b> and an externally threaded section <b>300</b>. The externally threaded section <b>300</b> is dimensioned such that it can be pushed through the boring <b>253</b>, whereby the latter has a countersunk, conical edge surface <b>302</b> facing in the distal direction so that a lower surface <b>304</b> of the head <b>298</b>, which is in the form of a countersunk head, is flush with the base <b>251</b>. Furthermore, the projection <b>228</b> is provided with a not illustrated blind hole boring which is coaxial to the longitudinal axis <b>232</b> so that the screw <b>296</b> can be screwed to the coupling member <b>226</b>.

A positioning device <b>306</b> on the implant component <b>214</b> comprises a ring-like set of teeth <b>308</b> which surrounds the projection <b>228</b> in ring-like manner and has a plurality of teeth <b>310</b> which point in the distal direction. An edge surrounding the blind hole <b>250</b> and defining a proximal end <b>252</b> of the adapter element <b>236</b> is likewise in the form of a set of teeth <b>312</b>, whereby the sets of teeth <b>308</b> and <b>312</b> are formed in mutually corresponding manner so that the teeth <b>310</b> of the set of teeth <b>308</b> can engage between the teeth <b>314</b> of the set of teeth <b>312</b> and vice versa. If the adapter element <b>236</b> is screwed to the implant component <b>214</b> by means of the screw <b>296</b>, then the positioning device <b>306</b> comprising the sets of teeth <b>308</b> and <b>312</b> holds the adapter element <b>236</b> in a defined rotary position relative to the implant component <b>214</b>. By loosening the screw <b>296</b>, the adapter element <b>236</b> can be moved away from the implant component <b>214</b> in parallel with the longitudinal axis <b>232</b> to such an extent that the sets of teeth <b>308</b> and <b>312</b> disengage and the adapter element <b>236</b> can then be rotated about the longitudinal axis <b>232</b> relative to the implant component <b>214</b>. For this purpose, a first guidance device <b>278</b> in the form of a rotary guide means <b>280</b> comprises the coupling member <b>226</b> and the blind hole <b>250</b>.

A distal half of the adapter element <b>236</b> is provided with a slot-like guide groove <b>256</b> which is open in the distal direction and oriented transversely relative to the longitudinal axis <b>232</b>. Inner side surfaces <b>316</b> of the guide groove <b>256</b> are provided with a respective set of teeth <b>318</b>, whereby the teeth extend in parallel with the longitudinal axis <b>232</b> and have a cuboidal profile in each case. Perpendicularly to the guide groove <b>256</b> and likewise perpendicularly to the longitudinal axis <b>232</b>, the side surfaces <b>316</b> are pierced by elongated holes <b>320</b>, these extending in a direction which is oriented parallel to the guide groove <b>256</b>. On an outer surface of the adapter element <b>236</b>, there is provided a respective elongated depression <b>322</b>, namely, in such a manner that there is formed a ring-shaped surface <b>324</b> of constant width which faces away from the longitudinal axis <b>232</b> and surrounds the elongated hole <b>320</b>.

The shaft <b>216</b> is elongated and rod-shaped and has a hemispherical rounded-off end <b>262</b> which points in the distal direction. At the proximal end of the shaft, there is a second coupling member <b>264</b> in the form of a substantially cuboidal projection <b>266</b>. Two side surfaces of the projection <b>266</b> facing transversely away from the longitudinal axis <b>268</b> of the shaft <b>216</b> form a part of the cylindrical outer surface of the shaft <b>216</b>. Outer surfaces <b>226</b> formed substantially perpendicularly to the aforesaid side surfaces and likewise facing transversely away from the longitudinal axis <b>268</b> are provided with a respective set of teeth <b>328</b> which corresponds to the set of teeth <b>318</b> and which comprises elongated rows of teeth extending in parallel with the longitudinal axis <b>268</b>. The construction and orientation of the sets of teeth <b>318</b> and <b>328</b> enables the shaft <b>216</b> to be moved into engagement with the adapter element <b>236</b> in different positions, namely, by a relative movement of the two parts towards one another in parallel with the longitudinal axis <b>268</b>.

Due to the construction of the projection <b>266</b>, two surfaces <b>270</b> are formed laterally thereof, these facing in the proximal direction and being oriented transversely relative to the longitudinal axis <b>268</b>. Moreover, the projection <b>266</b> is provided with a transverse boring which is oriented perpendicularly to the outer surfaces <b>326</b> whilst the longitudinal axis thereof intersects the longitudinal axis <b>268</b>. The boring together with a second fastening element <b>332</b> in the form of a cheese head screw <b>334</b> and a slide block <b>336</b> forms a securing device <b>286</b> for securing the shaft <b>216</b> to the adapter element <b>236</b> in the implantation disposition. The cheese head screw <b>334</b> has a head <b>338</b> and a threaded section <b>340</b> which protrudes perpendicularly away therefrom whilst the outer diameter thereof is matched to the width of the elongated holes <b>320</b> so that the threaded section <b>340</b> is displaceable in the elongated holes <b>320</b> transversely relative to the longitudinal axis <b>232</b>. The slide block <b>336</b> has a threaded boring <b>342</b> and is formed in such a manner that two parallel, flattened sides thereof can likewise be slid along mutually facing inner surfaces of the depressions <b>322</b> in a plane extending perpendicularly to the longitudinal axis <b>232</b>, without rotating, when the threaded section <b>340</b>, which is formed in corresponding manner to the threaded boring <b>342</b>, is screwed into the slide block <b>336</b>. The transverse boring <b>330</b> has an inner diameter which is matched to the outer diameter of the threaded section <b>340</b> so that the threaded section <b>340</b> can be passed through the elongated holes <b>320</b> and the transverse boring <b>330</b> and can be screwed to the slide block <b>336</b> when the projection <b>266</b> is pushed into the guide groove <b>256</b>.

An operating surgeon can also match the implant part <b>210</b> to the anatomy of a patient in a desired manner. For this purpose, the adapter element <b>236</b> is firstly fixed to the coupling member <b>226</b> of the implant component <b>214</b> with the aid of the screw <b>296</b> so that it is at least still possible to produce rotation about the longitudinal axis <b>232</b>. When the guide groove <b>256</b> is oriented in the desired manner, the screw <b>296</b> can be tightened so that the sets of teeth <b>308</b> and <b>312</b> engage together and produce and also maintain a defined rotary position of the adapter element <b>236</b> and the implant component <b>214</b> relative to each other. In a next step, the second coupling member <b>264</b> of the shaft <b>216</b> is slid into the guide groove <b>256</b>, namely, in such a manner that the longitudinal axis <b>268</b> and the longitudinal axis <b>232</b> exhibit the displacement <b>292</b> wanted by the operating surgeon. Due to the sets of teeth, the shaft <b>216</b> cannot of course be directly shifted in the guide groove <b>256</b> transversely relative to the longitudinal axis <b>268</b>, but rather, it is initially disengaged from the adapter element <b>236</b> in order to then be transferred by a translatory movement in a direction transverse or substantially transverse to the longitudinal axis <b>268</b> into another translatory position defined by a second positioning device <b>344</b> comprising sets of teeth <b>318</b> and <b>328</b>. In addition, the shaft <b>216</b> is adapted to be fixed immovably to the adapter element <b>236</b> in the implantation disposition with the aid of the securing device <b>286</b>.

A further exemplary embodiment of a modular implant part that is provided with the general reference symbol <b>410</b> is illustrated in <figref idrefs="DRAWINGS">FIGS. 9 to 11</figref>. It is in the form of a tibial part <b>412</b> of a knee joint prosthesis which, furthermore, comprises a femoral part that is not illustrated in the Figures, as well as a meniscus part that is provided with the general reference symbol <b>413</b>.

The implant part <b>410</b> comprises an implant component <b>414</b>, an elongated substantially round rod-shaped shaft <b>416</b> which is provided with notch-like flattened regions or depressions <b>417</b> that extend in parallel with its longitudinal axis <b>468</b> over almost the entire length of the shaft and are arranged such as to be displaced relative to each other through an angle of 120° with respect to the longitudinal axis <b>468</b> although they could optionally be dispensed with. Furthermore, the implant part <b>410</b> comprises a connecting device <b>418</b> for connecting the implant component <b>414</b> to the shaft <b>416</b>.

The implant component <b>414</b> comprises a plate that is substantially kidney-shaped in plan view and which forms a tibia plateau <b>420</b> the upper surface <b>422</b> of which is substantially flat in the exemplary embodiment illustrated in <figref idrefs="DRAWINGS">FIGS. 9 to 11</figref>. A lower surface <b>424</b> of the tibia plateau <b>420</b> is provided symmetrically with flat recesses <b>425</b> in order to save material and enable bone tissue to grow or to serve as an anchorage for bone cement, this thereby enabling the implant part <b>410</b> to be connected to the remaining part of the tibia of the patient in a particularly stable manner. Furthermore, the plate forming the tibia plateau <b>420</b> is provided with a peripheral edge <b>421</b> which is flush with the lower surface <b>424</b> and projects beyond the upper surface <b>422</b>, namely, by about the same amount as the plate is thick. On an inner surface <b>427</b> of the edge <b>421</b>, there are a plurality of recesses in the form of undercuts <b>429</b> which serve as latching members for cooperating with corresponding outwardly pointing projections <b>431</b> formed on the meniscus part <b>413</b> in order to enable the meniscus part <b>413</b> to be connected to the implant component <b>414</b> in latching manner. Extending away from the upper surface <b>422</b> of the meniscus part <b>413</b>, there are sliding surfaces <b>415</b> that are matched to the curvature of the condyle of a not illustrated femoral part of the knee joint prosthesis. The meniscus part <b>413</b> and the implant component <b>414</b> are thus connectable such as to be immovable relative to each other.

Due to the special shape of the recesses <b>425</b>, an approximately square surface region <b>433</b> is defined on the lower surface <b>424</b> through which there extends a boring <b>435</b> that defines a longitudinal axis <b>432</b>. The boring serves for accommodating a cylindrical bolt section of a first coupling member <b>426</b> which is provided with an external thread <b>430</b> and has a head <b>428</b> having substantially cuboidal slightly conical exterior surfaces. The bolt section is of a length such that it is adapted to pass through the boring <b>435</b> and be screwed into a nut <b>437</b> having an internal thread corresponding to the external thread <b>430</b>. In order to facilitate the task of screwing the first coupling member <b>426</b> into the nut <b>437</b>, the latter has two parallel flattened portions <b>441</b> that face in opposite directions and run parallel to the longitudinal axis <b>432</b>.

Moreover, the connecting device <b>418</b> includes an adapter <b>434</b> that comprises an adapter element <b>436</b> which is formed mirror-symmetrically relative to a mirror plane containing the longitudinal axis <b>432</b> and which has a flat upper surface <b>438</b> and a flat lower surface <b>440</b>. Coaxially relative to the longitudinal axis <b>468</b>, there is provided an internally threaded boring <b>442</b> which extends from the lower surface <b>440</b> up to a through opening <b>444</b> in the adapter <b>434</b> that runs transversely relative to the longitudinal axis <b>432</b>. In side view, the through opening <b>444</b> has a profile which is matched to that of the head <b>428</b>. In the upper surface <b>438</b> thereof, the adapter <b>434</b> is provided with a slot <b>446</b> the width of which corresponds to the diameter of the bolt section of the first coupling member <b>426</b> that is provided with the external thread <b>430</b>. Furthermore, inner walls of the adapter <b>434</b> which bound the through opening <b>444</b> and are formed adjacent to a lateral opening therein are provided with symmetrically facing returns <b>448</b> that enable the externally threaded portion <b>430</b> of the first coupling member <b>426</b> to be initially introduced from the side thereof which can be seen on the left of the adapter <b>434</b> in <figref idrefs="DRAWINGS">FIG. 11</figref>. The head <b>428</b> can thus be introduced into the through opening <b>444</b> which defines a guidance means therefor. The first coupling member <b>426</b> is displaceable transversely relative to the longitudinal axis <b>432</b> in the through opening <b>444</b> defining a linear guide means.

Due to the fact that the first coupling member <b>426</b> is adapted to be fixed to the tibia plateau <b>420</b> through the boring <b>435</b> in conjunction with the nut <b>437</b> in a defined manner, it is thus possible to adjust the adapter <b>434</b> relative to the tibia plateau <b>420</b> in such a manner that the adapter, the upper surface <b>438</b> of which is resting on the surface region <b>433</b>, is displaceable transversely relative to the longitudinal axis <b>432</b> when the implant part <b>410</b> has adopted its mounting disposition, i.e. when the nut <b>437</b> is not as yet clamping the first coupling member <b>426</b> against the tibia plateau <b>420</b> with maximum force. Moreover, rotation of the adapter <b>434</b> about the longitudinal axis <b>432</b> in the mounting disposition is also possible, whether or not any “offset” has been set. Here, “offset” means a lateral displacement between the longitudinal axis <b>432</b> and the longitudinal axis or axis of symmetry <b>468</b> of the internally threaded boring <b>442</b>.

The shaft <b>416</b> has a hemispherical rounded-off distal end <b>462</b>. The opposite end thereof carries a coupling element <b>472</b> in the form of a threaded bolt section <b>466</b>. Adjoining the latter on the distal side, there is a section <b>467</b> of reduced internal diameter which however, is stepped up again in the distal direction, whereby this widened section has a smaller outer diameter than the threaded bolt section <b>466</b>. As a consequence thereof, a ring-shaped surface <b>470</b> facing in the proximal direction is formed, i.e. in the direction of the tibia plateau <b>420</b>. This serves as a stop surface for a ring-like end face <b>456</b> of a collar sleeve <b>458</b> that has a conically tapering outer contour in the distal direction whilst the proximal end thereof likewise defines a ring-shaped surface <b>460</b> which rests against the lower surface <b>440</b>. The collar sleeve <b>458</b> is provided with a cylindrical boring <b>464</b> that is aligned coaxially with the longitudinal axis <b>468</b> whilst the internal diameter thereof is selected in such a manner that the collar sleeve <b>458</b> is adapted to be pushed over the proximal end of the shaft <b>416</b> until the end face <b>456</b> rests against the ring-shaped surface <b>470</b>. In addition, the height of the collar sleeve <b>458</b> parallel to the longitudinal axis <b>468</b> is smaller than the spacing between a proximal end face <b>469</b> of the threaded bolt section <b>466</b> running transverse to the longitudinal axis <b>468</b> and the ring-shaped surface <b>470</b>. Thus, the threaded bolt section <b>466</b> protrudes beyond the collar sleeve <b>458</b>, this thereby enabling the threaded bolt section <b>466</b> to be threaded into the internally threaded boring <b>442</b> of the adapter <b>434</b> for the purposes of connecting the shaft <b>416</b> to the adapter <b>434</b>.

The collar sleeve <b>458</b> makes it possible for different shafts <b>416</b>, which can differ in shape and length in particular, to be connected to the adapter <b>434</b>. In particular, it provides optimal support for the shaft <b>416</b> relative to the adapter <b>434</b>, namely, independently of manufacturing tolerances occurring during the production of the shaft <b>416</b>, in particular, at its proximal end comprising the threaded bolt section <b>466</b>.

Thus, in toto, the connecting device <b>418</b> is formed in such a manner that the shaft <b>416</b> is connectable to the implant component <b>414</b>, whereby, in a mounting disposition in which the nut <b>437</b> and the first coupling member <b>426</b> are not yet firmly screwed onto one another, the shaft <b>416</b> is adapted to be moved into different translatory positions by displacement of the adapter <b>434</b> in a direction transverse to the longitudinal axis <b>468</b>, i.e. by a translatory movement, and, in addition, it is adapted to be fixed immovably to the implant component <b>414</b> in one of the arbitrarily different translatory positions by tightening the nut <b>437</b> and the first coupling member <b>426</b>. In particular, the adapter is formed in such a manner that step-less adjustment of differing translatory positions is possible in the mounting disposition.

As previously mentioned, in the mounting disposition, the shaft <b>416</b> is rotatable about a rotational axis defined by the longitudinal axis <b>432</b> into different rotary positions relative to the implant component <b>414</b> by virtue of the special construction of the adapter <b>434</b> and, in the implantation disposition, it is adapted to be fixed to the implant component <b>414</b> in one of the different rotary positions due to the special construction of the connecting device. In the implantation disposition, the adapter <b>434</b> is adapted to be fixed both to the implant component <b>414</b> and to the shaft <b>416</b> in the manner described.

The adapter element <b>436</b> is formed symmetrically, namely, symmetrically relative to a plane of symmetry which contains the longitudinal axis <b>468</b> and is oriented at half the angle to planes defined by lateral inner surfaces of the through opening <b>444</b>. The implant component <b>414</b> comprises the first coupling member <b>426</b> which is in engagement in force-locking and/or shape-locking manner with the adapter <b>434</b> in the implantation disposition. The first coupling member <b>426</b> is in the form of a coupling projection when it is held on the implant component <b>414</b> by the nut <b>437</b>.

A first coupling device <b>454</b> for immovably fixing the adapter <b>434</b> to the implant component <b>414</b> is formed by the through opening <b>444</b> in combination with the slot <b>446</b>, the first coupling member <b>426</b> and also the boring <b>435</b> and the nut <b>437</b>. The first coupling device <b>454</b> comprises first coupling elements in the form of the through opening <b>444</b> as well as the first coupling member <b>426</b> the head <b>428</b> of which engages with the through opening <b>444</b> in the implantation disposition. The implant component <b>414</b> thus comprises the first coupling element in the form of the head <b>428</b> and the adapter <b>434</b>, a further first coupling element in the form of the through opening <b>444</b>. Thus, the first of the coupling elements comprises a recess in the form of the through opening <b>444</b> and the other coupling element comprises a projection in the form of the head <b>428</b> which enters the through opening <b>444</b> in the implantation disposition.

Furthermore, the connecting device <b>418</b> comprises a second coupling device <b>474</b> for immovably fixing the adapter <b>434</b> to the shaft <b>416</b> in the implantation disposition. The second coupling device <b>474</b> comprises two second coupling elements, namely, the internally threaded boring <b>442</b> and the coupling element <b>472</b> which are in engagement in the implantation disposition, namely, by a screw action, whereby the shaft <b>416</b> comprises the coupling element <b>472</b> in the form of the threaded bolt section <b>466</b> and the adapter <b>434</b> the internally threaded boring <b>442</b>. The adapter <b>434</b> and the first and second coupling elements comprised thereby in the form of the through opening <b>444</b> and the internally threaded boring <b>442</b> are formed in one piece.

Furthermore, the connecting device <b>418</b> comprises a first guidance device <b>478</b> for guiding a movement of the adapter <b>434</b> and the implant component <b>414</b> relative to each other in the mounting disposition in the manner described above. Furthermore, the first guidance device <b>478</b> comprises a rotary guide means <b>480</b> which enables the adapter <b>434</b> to be rotated about the longitudinal axis <b>432</b> relative to the implant component <b>414</b>. Furthermore, the first guidance device <b>478</b> comprises the first coupling member <b>426</b>.

Self-evidently, the shafts <b>16</b>, <b>116</b>, <b>216</b> and <b>416</b> described above can be fixed not only to an implant component comprising a tibia plateau, but also to an implant part <b>510</b> forming a femoral part <b>512</b> having a condyle body <b>520</b> comprising two artificial femoral condyles <b>522</b> which define articulation surfaces that are in contact with a not illustrated meniscus part of the knee joint prosthesis. An implant part of this type is illustrated exemplarily in <figref idrefs="DRAWINGS">FIG. 12</figref>. The shaft <b>516</b> can be connected by means of a connecting device <b>418</b> to the condyle body <b>520</b>. For this purpose, the latter includes a coupling member <b>526</b> which can be formed in identical manner to the coupling members <b>26</b>, <b>126</b> and <b>226</b>. Accordingly, the connecting device <b>518</b> can also be formed in identical manner to the connecting devices <b>18</b>, <b>118</b> and <b>218</b> described above. Then, in corresponding manner, the shaft <b>516</b> is also formed identically to the shafts <b>16</b>, <b>116</b> and <b>216</b> so that reference can be made to the above explanations for a detailed description thereof.

Optionally, the coupling member <b>526</b> can be inclined at an angle <b>535</b>, which can lie in a range from 0° to 15°, relative to a femur plateau <b>523</b> which is defined by a side of a projection-like body connecting the two femoral condyles <b>522</b>. Self-evidently, the respective longitudinal axes <b>32</b>, <b>132</b> and <b>232</b> of the coupling members <b>26</b>, <b>126</b> and <b>226</b> can be inclined relative to the surface-normals of the lower surfaces <b>24</b>, <b>124</b> and <b>224</b> of the respective implant components <b>14</b>, <b>114</b> and <b>214</b> in similar manner.

Common to all the modular implant parts described above, is that per se, both the implant component and the adapter element as well as the respective shaft can be formed at least mirror-symmetrically, and partly rotationally symmetrically.

Optionally, a plurality of shafts of different lengths can be provided for connecting to the respective implant component so that an implant part in the form of a set is in each case at the disposal of an operating surgeon, whereby each set comprises an implant component, an adapter and one or more shafts. All of the implant parts described above are made of a body-compatible material, preferably of a body-compatible metal.